[solatic]

Just to take an example from my current project - Postgres has ltree for hierarchical data: https://www.postgresql.org/docs/current/ltree.html , which has no SQLite equivalent.

Postgres is simply a much more feature-ful option. Going with database-per-tenant with e.g. Cloudflare D1 (besides the fact that D1 is still in beta, technically, but that's important when we're talking about databases) is a specific architectural decision that has its own tradeoffs (like making analytics much more difficult).